We found, that CMS built (copied from standard) custom category layout works well except product box style settings (Big Image, Minimal content don’t work. It stays Standard for the listing):
I tested this on my store. Changed the category template from „Big image“ to „Minimal content“. And it works. Shopware version 6.4.7.0.
The only thing I can think of: are you on the „correct“ language? (I’m new to SW so I’m not sure it’s possible to have different templates for different language).